Preparation of aluminum water treating product

ABSTRACT

A method of making a concentrated, stable aluminum compound containing water treatment product comprising reacting an aluminum compound in solution form with a phosphoric acid compound at a temperature in the range of about 15° C. to about 98° C., measuring the aluminum as aluminum oxide content and adding water to the reaction product if needed to prepare a product having an aluminum oxide content of about 10 percent by weight of the solution. The process is particularly advantageous in providing a system for the production of aluminum water treating products by recycling aluminum waste metal such as beverage containers utilizing a phosphoric acid medium.

[0001] This invention relates to aluminum products useful in watertreatment operation and to the methods for preparing such products. Moreparticularly, the invention relates to aluminum products whose watertreating properties are enhanced by a reaction of the aluminum contentwith a phosphorus reactant, particularly phosphoric acid.

BACKGROUND OF THE INVENTION

[0002] Various aluminum compounds, e.g. aluminum sulfate, aluminumchloride, aluminum nitrate and the like, are used for a variety of watertreatment purposes, such as to reduce turbidity, to remove color, toremove microorganisms, to reduce TOC (total organic carbon), to improvefiltration, as well as to produce benefaction of waters overall. Ingeneral, the aluminum material provides a coagulant that produces a flocin the aqueous medium that helps in the removal from the water byflotation, settling out, or various modes of filtration. The removedfloc includes various impurities and particles found in water, includingcolor-forming bodies. Some examples of such aluminum products incommercial operation are: treatment of potable water; waste waterprocessing for re-use of the water; paper treatment and sizing by papermanufacturers; processing operations in food industries, and the like.In view of the economic impact of water conservation and theincreasingly stringent regulations it is highly desirable to provide alow cost and more efficiently operable product medium and reaction thatcan be applied in existing water treatment facilities and that producesimproved results in terms of efficiently facilitating the purificationand general benefaction of waters.

SUMMARY OF INVENTION

[0003] While various methods are known for making and using additivessuch as aluminum sulfate, aluminum chloride and polyaluminum chloride,in the treatment of and to enhance the purity of waters derived fromvarious sources, the present invention provides a means to utilize avariety of aluminum sources heretofore regarded as not productive inpreparing additives of this type from raw materials, such as recycledaluminum. Waste aluminum metal, such as from beverage cans, foil, scrapaluminum, etc. heretofore generally regarded as not suitable for theproduction of water treating chemicals is effectively utilized inaccordance with the invention. The aluminum metal treated withphosphoric acid yields a product having excellent performance for watertreating applications.

[0004] We have discovered that a particular advantageous reactionproduct is obtainable from waste or recycled/recyclable aluminummaterials. Utilization of the invention resides in the production of thereaction product of such disposable aluminum that is treated with aphosphorus reactant. In producing the reaction product the aluminum tobe converted is preferably first treated with hydrochloric acid and thenreacted with a suitable phosphorus reactant

DETAILED DESCRIPTION OF THE INVENTION

[0005] The method of the invention involves stirring together analuminum compound whether the dissolved metal itself or alum (aluminumsulfate), aluminum chloride or polyaluminum chloride and phosphoric acidat a temperature between 60° and 110° C., but preferably about 90° C.and about 98° C. until the aluminum metal has dissolved. The reactionproduct is cooled and filtered, and the aluminum content measured. Theproduct solution based on alum can be maintained as a solution atconcentrations exceeding 9% to >13% Al as Al₂O₃ in alum as compared tosolutions that are not treated with a phosphorus reactant and whichresult in solidification at room temperature at concentration above8.3%-805% aluminum oxide (Al₂O₃). Where appropriate for use the reactionproduct of the invention may be diluted with water to make a productsolution suitable for intended use.

[0006] The preferred method of the invention comprises reacting thealuminum solution or slurry that has been treated with hydrochloric acidand containing from about 75 to about 94 weight percent, preferablyabout 85 to about 90% by weight, of aluminum compound and about 2% toabout 10% of 85% by weight (commercial), of phosphoric acid. Thestarting materials are stirred together while maintaining suitabletemperatures, and the reaction product solution is filtered. Thisreaction comprises a rapid, low cost method; the starting materials areinexpensive and readily available; the reaction time is generally lessthan four hours; and only a moderate input of external heat is required.Unexpectedly, we have also found that this product is effective at arelatively low dosage to remove turbidity. The product is accordinglyhighly efficient for forming floc and removing fine particles. Ingeneral, the invention provides an inexpensive product that utilizesrecycled aluminum and can be used to treat water at low doses, i.e. wellbelow about 40 ppm, resulting in a turbidity level after settling ofbelow 2.5 NTU (Nephelometric Turbidity Units). Commercially availableproducts of comparable effectiveness are much more expensive to produce,are not as stable, and require special handling procedures as analternative, when aluminum chloride is employed it can be prepared insitu from hydrochloric acid and aluminum trihydrate for example.

[0007] In the preferred method, aluminum metal is treated withhydrochloric acid. The phosphoric acid is then added and the mixture isstirred for 4-8 hours and filtered through a 1-5 micron filter to removeany insoluble particles. In the reaction, the phosphoric acid is addedslowly to the aluminum solution. The temperature is preferably monitoredto prevent sharp increases in temperature; once the reaction isinitiated any external heat source may be discontinued or reduced to alevel sufficient to maintain the reaction. The phosphoric acidfacilitates the dissolution and aids in keeping the temperature of thereaction mixture uniform to provide a product whose performance hassuperior commercial utility.

[0008] The resultant product can be used to treat all types of water,including potable and waste waters, water used in paper manufacture andsizing, and water used in the food industries and agriculture, forexamples, to remove particles and color-forming bodies, to reduceturbidities and TOC and to increase filtering capacities.

[0009] After forming the aluminum reaction product solution, thealuminum oxide content is measured and the solution diluted with waterif necessary to obtain an aqueous product having a basicity of fromabout 38.5 to about 65, and an aluminum oxide content of about 10% to15%.

[0010] The present process is highly advantageous because its low coststarting materials produces an economical product that cleans andotherwise treats water efficiently by lowering turbidity levels at lowdosage levels, and increasing filtering capacities.

[0011] The invention will be further described in the followingexamples; however, the invention is not meant to be limited to thedetails described therein.

EXAMPLE 1

[0012] Reagents

[0013] 1. 114.4 grams Concentrated Hydrochloric Acid

[0014] 2. 260.1 grams Water

[0015] 3. 35 grams used aluminum metal container that comprises shreddedaluminum cans

[0016] 4. 30 grams 85% phosphoric acid

[0017] 5. 60.5 grams Water

[0018] Sequence of Method Steps

[0019] 1. The Concentrated HCl (114.4 g) and initial quantity (260.6 g)of de-ionized water are introduced into a suitable reaction vessel

[0020] 2. The acid/water solution is heated to 90° C.

[0021] 3. The aluminum metal (35 grams) is added and the temperaturemaintained at 95° C. for about 2.0 to 2.5 hours or until the reactionmixture is clear, i.e., until all aluminum metal is dissolved

[0022] 4. To this solution 30 grams of phosphoric acid and the balance(62.5 g) of the de-ionized water are added and the reaction is continuedat approximately 80° C. for about 45 minutes. Note that if there issignificant reaction of the phosphoric acid with the initial solution,such as evolution of hydrogen (bubbles) or an increase in reactiontemperature, suspend the further addition of phosphoric acid and allowthe aluminum solution to continue reaction with HCl. Addition of therest of H₃PO₄ may resume after the reaction subsides.

[0023] 5. Cool and, if necessary, filter

[0024] The reaction product characteristics are as follows:

[0025] pH 2.4

[0026] Aluminum 13.1% as Al₂O₃ (Target 11%)

[0027] Basicity 55% (Target 55%)

[0028] Specific Gravity 1.232

[0029] Clear to slightly yellow solution

[0030] The following aluminum sources have been successfully used withthe above described procedure:

[0031] Aluminum cans, tops removed, shredded

[0032] Aluminum hydroxide

[0033] Aluminum shot<10 mm diameter

[0034] Aluminum shot, recycled 3-15 mm diameter

[0035] Although phosphoric acid is the preferred phosphoric reactant avariety of other phosphorus providing reactants such as sodiumphosphate, monobasic (NaH₂PO₄*nH₂O;n≧0), sodium phosphate, tribasicNa₃PO₄*nH₂O;n≧0), sodium phosphate dibasic Na₂HPO₄*nH₂O;n>0), calciumphosphate, (Ca₃(PO₄))₂*nH₂O;n>0), (CaHPO₄*nH₂O;n>0) and the like. Monobasic, dibasic and tribasic potassium phosphates may also be suitablyutilized.

EXAMPLE 2a, 2b, 2c and 2d

[0036] Reagents

[0037] The following describes the aluminum sulfate preparation for eachexample:

[0038] 1. 100 grams Aluminum trihydrate plus additional of 15 or 20grams as described below for the individual examples. Appropriateamounts of bauxite or other aluminum source that provides an equivalentAluminum content may be substituted.

[0039] 2. 110 grams water

[0040] 3. 200-210 grams of 93% sulfuric acid, or equivalent dosage ofweaker or stronger acid, adjusting the quantity of water with weakeracids

[0041] 4. Sufficient water to maintain a suitable volume and to adjustto the appropriate acid strength at end of reaction

[0042] Phosphoric Acid/Phosphate Additions

EXAMPLE 2a

[0043] 15 grams additional aluminum trihydrate were used plus 15 gramsof phosphoric acid plus sufficient water to adjust for the appropriatestrength at the end of the reaction.

EXAMPLE 2b

[0044] 15 grams additional aluminum trihydrate were used plus 50 gramsof phosphoric acid and sufficient water to adjust to the appropriatestrength at the end of the reaction.

EXAMPLE 2c

[0045] 15 grams additional aluminum trihydrate were used plus 75 gramsphosphoric acid and sufficient water to adjust to the appropriatestrength at the end of the reaction.

EXAMPLE 2d

[0046] 15 grams additional aluminum trihydrate were used plus 150 gramsphosphoric acid and sufficient water to adjust for the appropriateacidity strength at end of reaction.

[0047] See Phosphate source notes in example 1 for variations

[0048] Procedure

[0049] 1. Sulfuric acid is added to initial charge of water

[0050] 2. Aluminum trihydrate (115 to 120 grams) is added slowly andallowed to react for 2-2.5 hours with continuous mixing

[0051] 3. Water is added to keep volume to at least 300 ml

[0052] 4. At the end of reaction, phosphoric acid is added in amounts asspecified above for each of examples 2a, 2b, 2c, 2d and mixing iscontinued for up to about one hour

[0053] 5. Sufficient water is added to adjust to the desired and theproduct is cooled and filtered if necessary.

[0054] The following comprise the product characteristics

[0055] pH 2-3

[0056] Aluminum content 9-11% as Al₂O₃

[0057] Specific Gravity 1.2-1.35

[0058] Clear to slightly yellow appearance

EXAMPLE 3

[0059] 463g AlCl₃ aluminum chloride

[0060] 148.5 g DIH₂O deionized water

[0061] 20.8 g of aluminum shot having a 3-15 mm size obtained fromPilgrim Recycling

[0062] 632.3 g total reagents

[0063] The components are mixed and react @ 106-110° C. for 6 hoursminimum

[0064] The reaction product had the analysis set forth in Table I TABLEI % Al₂O₃ 15.61 % basicity 49.88 pH 1.64 Jar test Passes Specificgravity 1.305

EXAMPLE 4

[0065] The following ingredients and order of additives were used:

[0066] 114.5 g conc HCl

[0067] 260.6 g of deionized water

[0068] 35 g of aluminum shot (obtained from Reynolds metals Co. −6+20lot #426999)

[0069] 30 g phosphoric acid

[0070] 62.5 g of deionized water

[0071] 502.6 g

[0072] Procedure

[0073] 1. Add HCl and initial quantity (260.6 g) of deionized water tothe reactor and heat to 90° C.

[0074] 2. Add the aluminum and react the mixture at 95° C. for about 2.5hours or until a clear color is present. Then add the H₃PO₄-H₂O mix andthen react @ 85° C. for 1 hour. Cool, remove and filter.

[0075] The results are set forth in TABLE II. TABLE II % Al₂O₃ 13.94 %basicity 61.13% 61.13 PH 2.83 S.G. 1.257

EXAMPLE 5

[0076] The following ingredients and order of addition were used:

[0077] 114.5 g conc HCl

[0078] 235 g deionized water

[0079] 60 g aluminum shot (Reynolds −6+20)

[0080] 30 g phosphoric acid and

[0081] 362.5 g of deionized water

[0082] 602 g total reagents

[0083] Procedure

[0084] 1. Add HCl and initial H₂O to a suitable reactor, and heat to 90°C.

[0085] 2. Introduce the aluminum shot and react @95° C. for about 2.5hours or until clear, then add H₃PO₄/H₂O mix and react @ 80° C. for 1hour. The product is the removed and filtered and the properties shownin TABLE III. TABLE III Al₂O₃ 22.7 Basicity 73.1 1.389 1.389

EXAMPLE 6

[0086] Ingredients:

[0087] 420 g AlCl₃ aluminum chloride (GenPac1000 obtained from GenTekInc)

[0088] 145 g deionized water

[0089] 42 g aluminum trihydrate

[0090] 607 g total ingredients

[0091] Procedure

[0092] 1. Add AlCl₃ and 50 g of the deionized water to a suitablereactor and heat to 100° C.

[0093] 2. Then mix the remaining H₂O (95 g) with the trihydrateintroduce into the reactor and react at 115° C. for 6 hours.

[0094] The product characteristics are shown in TABLE IV. TABLE IV %Al₂O₃ 12.73% % basicity 20.29% pH 0.20 S.G. 1.312

EXAMPLE 7

[0095] Ingredients:

[0096] 430 g AlCl₃

[0097] 148.5 g deionized water

[0098] 20.8 g aluminum shot (Reynolds metals Co.) −6+20 lot #42-6999

[0099]599.3 g total ingredients

[0100] Procedure:

[0101] 1. The ingredients were introduced and mixed in a suitablereaction vessel at 105-106° C. for 6 hours minimum.

[0102] The product characteristics are shown in TABLE V. TABLE V Al₂O₃15.32 % basicity 49.72 pH 1.67 Jar test Passes Specific gravity 1.301

EXAMPLE 8

[0103] Ingredients:

[0104] 420 g AlCl₃

[0105] 100 g deionized water

[0106] 40 g aluminum trihydrate

[0107] 560 g total ingredients

[0108] Procedure:

[0109] 1. The aluminum chloride is added to a suitable reactor andheated to 110° C.;

[0110] 2. Then add the 40 g hydrate/with the 100 g deionized water tothe reactor; and

[0111] 3. Continue the reaction at 115° C. for 6 hours.

[0112] The product properties are set forth in TABLE VI. TABLE VI Al₂O₃14.33 Basicity 28.4 S.G. 1.32 pH 0.01

EXAMPLE 9

[0113] Ingredients:

[0114] 420 g AlCl₃ (GenPac 1000)

[0115] 145 g deionized water

[0116] 42 g aluminum trihydrate

[0117] 12 g aluminum powder (obtained from Fisher Scientific)

[0118] 619 g total weight of ingredients

[0119] Procedure:

[0120] 1. The aluminum chloride and 50 g of the deionized water areintroduced to a suitable vessel and heated to 110° C.

[0121] 2. The water and trihydrate mix of 95 g of deionized water and 42g aluminum trihydrate are mixed and added to the reactor and heated.Heating is continued at 135° C. for 5-6 hours.

[0122] 3. The aluminum powder is introduced into the reactor slowly overa period of about 4 hours while observing the reactive temperature andcontrolling excessive H₂ generation and bubbles with a dI water spray.

[0123] The product properties are set forth in TABLE VII. TABLE VII %Al₂O₃ 14.96 % Basicity 24.33 pH 0.12 S.G. 1.349

[0124] Although the invention has been described in terms of particularembodiments, blends of one or more of the various additives describedherein can be used, substitutes therefor, as will be known to thoseskilled in the art. Thus the invention is not meant to be limited to thedetails described herein, but only by the scope of the appended claims.

What is claimed:
 1. A method of producing an aluminum water treatmentproduct comprising: a) dissolving an aluminum compound by liquefying asolid aluminum compound in an acid medium at a temperature of about 20°C. to about 125° C., b) reacting the aluminum reaction solution withfrom about 1 to about 10 weight percent of a phosphorus compound; and c)diluting the resultant reaction product with water to make a productsolution containing about 23% by weight of aluminum as aluminum oxide(Al₂O₃) and having a basicity of from about 30 to 85 percent.
 2. Amethod according to claim 1 wherein said phosphorus compound isphosphoric acid (85% phosphoric acid)
 3. A method according to claim 1wherein said aluminum compound comprises recycled aluminum.
 4. A methodaccording to claim 3 wherein said recycled aluminum are beveragecontainers.
 5. A method according to claim 2 wherein the phosphoruscompound is phosphoric acid.
 6. The method according to claim 1 whereinthe acid medium comprises hydrochloric acid.
 7. The method according toclaim 1 wherein the acid medium comprises sulfuric acid.
 8. The methodof claim 2 wherein the acid medium is hydrochloric acid.
 9. The methodof claim 2 wherein the acid medium is sulfuric acid.
 10. The method ofclaim 6 wherein the aluminum compound is aluminum metal.
 11. The methodof claim 1 wherein the aluminum compound is recycled or recoveredaluminum hydroxide.
 12. The method of claim 7 wherein the acid medium analuminum compound are supplied by aluminum sulfate.
 13. The method ofclaim 1 wherein aluminum sulfate, liquid comprise is the dissolvealuminum compound of step (a).